单宁酸对淡色库蚊抗氰戊菊酯品系和敏感品系幼虫生长发育的影响

单宁酸是一种植物次生代谢物, 为探索其用于蚊幼虫防治的可能性,在室内测定了其对淡色库蚊Culex pipiens pallens抗氰戊菊酯品系和敏感品系1～4龄幼虫的毒性,并观察了其对存活幼虫生长发育的影响。结果表明,淡色库蚊敏感品系幼虫对单宁酸的敏感性比抗氰戊菊酯品系的要高,1～4龄幼虫分别高6.4、4.9、4.7和2.0倍。4个龄期幼虫中,无论是敏感品系还是抗氰戊菊酯品系,均是1龄幼虫对单宁酸的敏感性最高,3龄幼虫最低。在1 000 mg/L单宁酸持续作用下,敏感品系和抗氰戊菊酯品系各龄幼虫的存活率,均随处理时间延长而降低。与对照相比,饲养在100 mg/L～500 mg/L单宁酸溶液中的存活幼虫发育历期延长,敏感品系和抗氰戊菊酯品系发育历期分别延长了34.5～38.3 h和59.2～93.4 h。其中,125 mg/L浓度处理的敏感品系1～4龄幼虫,其发育历期与对照的差异达到了显著水平(P<0.05);抗性品系则在250 mg/L作用下也达到了差异显著水平(P<0.05)。但100～250 mg/L单宁酸处理淡色库蚊抗氰戊菊酯品系和敏感品系1龄幼虫,对其存活幼虫的化蛹率、羽化率和成虫性比均无显著影响。表明单宁酸对淡色库蚊幼虫的影响主要是延迟其生长发育,且影响程度与蚊虫对氰戊菊酯的敏感性有关。     

Analysis of precocious metamorphosis induced by application of an imidazole derivative to early third instar larvae of the silkworm,Bombyx mori

When an imidazole derivative (KK-42) was applied to day 1 third instar larvae of the silkworm, Bombyx mori, 100% underwent precocious metamorphosis at the end of the fourth instar. Thus, the fourth instar becomes the last instar in these KK-42–treated larvae. The endocrine systems underlying the precocious metamorphosis were analyzed in the present study. Hydroprene application during the prolonged third instar after KK-42 treatment can prevent precocious metamorphosis, and the results showed dose-dependent and stage-specific effects. From analysis of the developmental changes in ecdysteroid levels in both KK-42–treated larvae and KK-42– and hydroprene-treated larvae, we conclude that changes in JH levels during the third larval instar can modify the secretion pattern of prothoracic glands and that during the next larval instar, very low ecdysteroid levels during the early stages of the presumptive last (fourth) larval instar are directly related to precocious metamorphosis. Arch. Insect Biochem. Physiol. 36:349–361, 1997. © 1997 Wiley-Liss, Inc.     

Evaluation of the naturally-derived insecticide spinosad against Culex pipiens L. (Diptera: Culicidae) larvae in septic tank water in Antalya, Turkey.

The naturally-derived insecticide spinosad (Conserve SC) was evaluated against larval Culex pipiens L. (Diptera: Culicidae) under laboratory and field conditions in Antalya, Turkey. Laboratory bioassays showed that the 24 h LC50 and LC90 against late 3rd and early 4th instars were estimated at 0.027 and 0.111 parts per million, respectively, while adult emergence was eliminated at concentrations above 0.06 ppm. Larval mortality from septic tanks that were treated with spinosad at rates of 25, 50, 100, and 200 g ai/ha ranged between 22 to 78% 1 day after application. At 7 days post-treatment, larval mortality ranged from 2 to 50% and at 14 days mortality was <10% for all treatments. Larval bioassays of the water from those septic tanks treated at 100 and 200 g ai/ha resulted in an elimination of Cx. pipiens larvae 7 days after treatment. After this time, larval reduction declined to 79 and 83%, respectively, 14 days after treatment. Larval reduction in septic tanks treated at the two lowest rates (i.e. 25 and 50 g ai/ha) ranged from 14 to 74% during the 14-day study. These results indicated that spinosad can be considered an effective larvicide for treatment of septic tanks against Cx. pipiens.     

Biological and biochemical characteristics for quality control of Harmonia axyridis (Pallas) (Coleoptera, Coccinellidae) reared on a liver-based diet

Biological and biochemical parameters of a flightless strain of Harmonia axyridis, fed on a pork liver-based artificial diet and on Ephestia kuehniella eggs as controls, were compared. The diet-grown larvae showed a significantly longer developmental time and a lower adult emergence rate compared to control larvae. The weights of the newly emerged adults were significantly higher for adults fed E. kuehniella eggs during their larval stages than fed the artificial diet. In contrast, larval food source had no effect on the duration of the pre-oviposition period or adult longevity. For adults fed on E. kuehniella eggs as larvae, a significantly longer pre-oviposition period, lower daily weight gain and fecundity were found for the diet-fed females compared to those fed on E. kuehniella eggs throughout the life span. The adult food source had no significant effect on longevity and fertility. Lower amino acid and fatty acid contents (in particular C16:1 and C18:3n-3) were found for the prepupae and newly emerged females obtained from diet-reared larvae compared to controls. Deficiencies in fatty acids C16:1 and C18:3n-3 were also observed in females obtained from E. kuehniella egg-reared larvae and fed on diet from adult emergence. The analyses of the foods showed deficiencies in artificial diet, especially for some amino and fatty acids. The results suggest a non-optimal composition of the artificial diet and some possibilities for its improvement. However, this polyphagous predator could be reared from first instar larvae to fully reproductive adults on a pork liver-based artificial diet.     

亚致死剂量阿维菌素和氟虫睛处理小菜蛾对寄生蜂菜蛾绒茧蜂生长发育的影响

分别在小菜蛾体内的菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾2龄幼虫亚致死剂量（＝LC₁₀）的阿维菌素和氟虫睛,研究上述杀虫剂处理对寄主体内菜蛾绒茧蜂结茧率和羽化率的影响。结果表明： 在菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾LC₁₀剂量阿维菌素处理的菜叶后,菜蛾绒茧蜂的结茧率分别下降26.6%,22.8%和5.8%,饲喂小菜蛾LC₁₀剂量氟虫睛处理的菜叶后,菜蛾绒茧蜂的结茧率分别下降76.9%,42.5%和18.5%。上述阿维菌素处理对菜蛾绒茧蜂成虫羽化率影响不显著,但上述氟虫睛处理可显著抑制菜蛾绒茧蜂成虫羽化率,在菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾LC₁₀ 剂量氟虫睛处理的菜叶可导致菜蛾绒茧蜂成虫羽化率分别下降53.1%,36.1%和47.8%。结果显示,即便是对寄主小菜蛾幼虫很低的剂量（LC₁₀剂量）也会显著危害小菜蛾幼虫体内的菜蛾绒茧蜂的生长发育。此外,饲喂小菜蛾幼虫亚致死剂量杀虫剂对菜蛾绒茧蜂生长发育的影响与杀虫剂种类及蛾绒茧蜂发育阶段有关。     

Effect of body size on energy reserves in Culex pipiens pallens females (Diptera: Culicidae)

We examined the relationship between body size and energy reserves of female Culex pipiens pallens under laboratory conditions. Small and large‐sized adult mosquitoes were obtained from larvae reared at different densities. There was a significantly positive relationship between pupal body weight and adult wing length depending on body sizes. Studies showed large females contained significantly higher contents of glycogen and lipid but lower protein stores in comparison to small females. Large sized mosquitoes accumulated higher percentages of glycogen (21.2% vs 15.9%) and lipid (45.8% vs 30.7%) but lower levels of protein (33.0% vs 53.4%) than small females. This result suggests that larval‐derived glycogen and lipid stores may be important in determining the body size of female Cx. pipiens pallens.     

The haemagglutination activity in the different developmental stages and changes of this activity caused by analogues of insect hormones in two members of the Culex pipiens complex of mosquitoes

Abstract. Haemagglutination activity was studied in last larval instars, pupae and adults of both sexes of the Culex pipiens mosquito complex. In females of Culex pipiens quinquefasciatus Say, an anautogenous member of C. pipiens complex, activity was detected in the homogenate of the head‐thorax complex, gut and remaining abdomen (after removing the gut), before and after sucking water, glucose solution or blood. Similar investigations were made in females of autogenous Culex pipiens molestus Forskal, a member of the same mosquito complex. The results were compared with data obtained for males of these subspecies, plus the larvae and pupae. The results show that haemagglutination activity in adult females depends not on the sucking of blood, but on the age of the females. In newly emerged females, the level of activity was very low, but after 24 h or 48 h of activity was highly enhanced, even in females that had no possibility to suck water or other liquids including blood. Furthermore, in C. p. molestus, the haemagglutination activity does not change in hungry or engorged females, and a high level of activity was found in the gut of last larval instars, a developmental stage that never takes blood. Treatment with methoprene reduces haemagglutination activity in both sexes, but 20‐hydroxycdysone application decreased activity in the gut of females. It is suggested that haemagglutination activity may be regulated indirectly by the endocrine system. The possibility that haemagglutination activity may depend on some aspect of the digestive system that has no direct connection to blood uptake is discussed. In addition, the activity may be important not only for the elimination of infections, but also for the processing of food and the utilization and transport of nutrients.     

A systematic study on hemocyte identification and plasma prophenoloxidase from Culex pipiens quinquefasciatus at different developmental stages

Culexpipiens quinquefasciatus (C. quinquefasciatus) is an important vector that can transmit human diseases such as West Nile virus, lymphatic filariasis, Japanese encephalitis and St. Louis encephalitis. However, very limited research concerning the humoral and cellular immune defenses of C. quinquefasciatus has been done. Here we present the research on hemocyte identification and plasma including hemocyte prophenoloxidase from C. quinquefasciatus at all developmental stages in order to obtain a complete picture of C. quinquefasciatus innate immunity. We identified hemocytes into four types: prohemocytes, oenocytoids, plasmatocytes and granulocytes. Prophenoloxidase (PPO) is an essential enzyme to induce melanization after encapsulation. PPO-positive hemocytes and plasma PPO were observed at all developmental stages. As for specific hemocyte types, prophenoloxidase was found in the plasmatocytes at larval stage alone and in the smallest prohemocytes during almost all developmental stages. Moreover, the granulocytes were PPO-positive from blood-fed female mosquitoes and oenocytoids were observed PPO-positive in pupae and in adult females after blood-feeding. As for plasma, there were different patterns of PPO in C. quinquefasciatus at different developmental stages. These results are forming a basis for further studies on the function of C. quinquefasciatus hemocytes and prophenoloxidase as well as their involvement in fighting against mosquito-borne pathogens.     

粘虫幼虫密度对成虫能源物质含量的影响

通过粘虫Mythimna separata幼虫密度(1头/瓶、20头/瓶、40头/瓶)对成虫水分、甘油酯和糖原含量影响的研究结果。不同幼虫密度处理的初羽化成虫水分含量无明显差异,但1～5日龄40头/瓶的雄蛾及1～3日龄雌蛾高于单头处理的;20、40头/瓶的初羽化成虫甘油酯含量没有显著的差异,但均显著地高于单头饲养的;20头/瓶羽化的雌、雄成虫l～5日龄甘油酯含量随日龄的增加而增加,到5日龄达到最大值后才开始下降,40头/瓶的在3日龄达到最大值后即开始下降,而单头饲养羽化的在1日龄达到较高值,2日龄降至最低后再缓慢回升。幼虫密度对初羽化成虫及1～7日龄雄蛾的糖原含量没有显著的影响,但20、40头/瓶条件下羽化的1～7日龄雌蛾糖原含量随日龄的增加而增加,而单头饲养的则随日龄的 增加而下降。这些结果表明幼虫密度不仅影响到初羽化成虫能源物质的含量,而且也可能影响到成虫能源物质特别是甘油酯的代谢。     

Physiological and morphological aspects of Aedes aegypti developing larvae: effects of the chitin synthesis inhibitor novaluron

Population control of the dengue vector mosquito, Aedes aegypti, is difficult due to many reasons, one being the development of resistance to neurotoxic insecticides employed. The biosynthesis of chitin, a major constituent of insect cuticle, is a novel target for population control. Novaluron is a benzoylphenylurea (BPU) that acts as a chitin synthesis inhibitor, already used against mosquitoes. However, information regarding BPU effects on immature mosquito stages and physiological parameters related with mosquito larval development are scarce. A set of physiological parameters were recorded in control developing larvae and novaluron was administered continuously to Ae. aegypti larvae, since early third instar. Larval instar period duration was recorded from third instar until pupation. Chitin content was measured during third and fourth instars. Fourth instars were processed histochemically at the mesothorax region, stained with hematoxylin and eosin (HE) for assessment of internal tissues, and labeled with WGA-FITC to reveal chitinized structures. In control larvae: i) there is a chitin content increase during both third and fourth instars where late third instars contain more chitin than early fourth instars; ii) thoracic organs and a continuous cuticle, closely associated with the underlying epidermis were observed; iii) chitin was continuously present throughout integument cuticle. Novaluron treatment inhibited adult emergence, induced immature mortality, altered adult sex ratio and caused delay in larval development. Moreover, novaluron: i) significantly affected chitin content during larval development; ii) induced a discontinuous and altered cuticle in some regions while epidermis was often thinner or missing; iii) rendered chitin cuticle presence discontinuous and less evident. In both control and novaluron larvae, chitin was present in the peritrophic matrix. This study showed quantitatively and qualitatively evidences of novaluron effects on Ae. aegypti larval development. To our knowledge, this is the first report describing histological alterations produced by a BPU in immature vector mosquitoes.     

Oxygen consumption in mosquito larvae parasitized by Romanomermis culicivorax (Nematoda)

The effect of parasitism by Romanomermis culicivorax on the oxygen consumption of three species of mosquito larvae was studied by manometric methods. The Q02 of Culex pipiens, both parasitized and unparasitized, decreased as the host larvae developed from the second to fourth instar. In the early stages there was no significant difference in Q02 in parasitized and unparasitized hosts but the Q02 increased significantly in parasitized fourth instar larvae. The Q02 of parasitized and unparasitized fourth instars of Aedes taeniorhynchus, Anopheles quadrimaculatus and C. pipiens were compared. The Q02 of all parasitized hosts was significantly increased and the Q02 of the two culicine species displayed a dramatic increase in oxygen consumption. The oxygen consumption of the parasitic mermithid larvae was estimated from that obtained earlier for the post-parasitic larvae but did not account for more than 9-36% of the increased Q02 of the parasitized hosts. On this basis it seems probable that the increased metabolic rate as reflected by oxygen consumption of the parasitized mosquito larve was principally a manifestation of the physiological and nutritional stress induced by the mermithid nematodes.     

Reciprocal transplantation of wing discs between a wing deficient mutant (fl) and wild type of the silkworm, Bombyx mori

The wingless mutant flügellos ( fl ) of the silkworm lacks all four wings. Although wing discs of the fl seem to develop normally until the fourth larval instar, wing morphogenesis stops after the fourth larval ecdysis, probably caused by aberrant expression of an unidentified factor, referred to as fl . To characterize factor fl , the wing discs dissected from the wild-type (WT) and fl larvae were transplanted into other larvae and developmental changes of the discs were examined. When the wing disc from a WT larva was transplanted into another WT larva and allowed to grow until emergence, a small wing appeared that was covered with scales. Thus, the transplanted wing discs can develop autonomously, form scales and evert from adult skin. The WT wing discs transplanted into the fl larvae also developed at a high rate. However, the fl wing discs transplanted into the WT larvae did not develop during the larval to pupal developmental stages. These data suggest that the fl gene product (factor fl) works in the wing disc cells during wing morphogenesis. Its function cannot be complemented by hemolymph in the WT larva. It is also implied that the level of humoral factors and hormones required for wing morphogenesis are normally maintained in the fl larva.     

Developmental and sex-dependent regulation of storage protein synthesis in the silkworm,Bombyx mori

The mechanism of sex-dependent expression of a major plasma protein, referred to as storage protein 1 (SP-1) was studied during development of the silkworm, Bombyx mori. SP-1 occurred in the hemolymph of the female as well as in the male larvae until the end of the fourth larval instar. In the last instar larvae, the amount of SP-1 in the hemolymph greatly increased in females, but markedly declined in males. The level of fat body mRNA for SP-1 reflected the developmental and sex-dependent changes in the hemolymph concentration of SP-1. The developmental patterns of hemolymph proteins in the third and the fourth instar larvae of sex-mosaic individuals were quite analogous to those observed in normal larvae at the same developmental stages. The hemolymph concentration of SP-1 at the last larval instar of the sex mosaics varied among individuals irrespective of the gonad compositions. In vitro culture of the fat body cells dissected from several locations of a sex-mosaic larva provided evidence that each fat body cell in a common hemolymph milieu synthesizes a high (female type) or a low (male type) level of SP-1 depending on the sex chromosome composition. The amount of vitellogenin in the hemolymph of the sex-mosaic pupae was in proportion to that of SP-1 at the last larval instar. From these results, it is suggested that the sex-dependent expression of SP-1 and vitellogenin in B. mori is genetically determined and developmentally regulated without participation of the reproductive organs or any sex-specific humoral factors.     

幼虫密度对甜菜夜蛾生长发育与繁殖的影响

为了研究甜菜夜蛾Spodoptera exigua(Hübner)幼虫的密度对其发育及繁殖的影响,本实验观察了5种幼虫密度下（1,5,10,20,30头/瓶）,幼虫发育和成虫繁殖情况。结果表明：幼虫和蛹历期、存活率和蛹重均差异显著。幼虫和蛹历期均以20头/瓶的最短,1头/瓶的最长,其余随幼虫密度增加而延长;幼虫至蛹存活率以10头/瓶的最高,其余随幼虫密度增加而降低;1头/瓶的蛹最重,显著高于其他密度的,其余随幼虫密度增加而下降。尽管密度间成虫羽化率和产卵前期均无显著差异,但成虫产卵量、寿命和畸形率差异显著。1头/瓶的产卵量最多,其次为10头/瓶的,其余随幼虫密度增加而减少,30头/瓶的产卵量显著少于其他密度的; 密度在1～20头/瓶范围内,雌蛾寿命均较短,显著短于30头/瓶的,而雄蛾寿命以5头/瓶的最短,显著短于其他密度的（10头/瓶除外）,10头/瓶的次之,其余密度间差异不显著;不同幼虫密度下羽化的成虫畸形率差异显著,10头/瓶的最低,其余随幼虫密度增加而升高; 生命表结果表明甜菜夜蛾在10头/瓶下世代存活率和种群增长指数均最高,幼虫密度过低或过高均不利于种群增长;世代存活率（S）和种群增长指数（I）与幼虫密度之间的关系均呈抛物线关系：S =－0.2087x²+2.5694x+211.52 (R²=0.88),I=－0.0552x²+0.9166x+54.168 (R²=0.95)。结果提示幼虫密度影响甜菜夜蛾种群动态的重要生态因子之一。     

Rearing density and susceptibility of Rana pipiens metamorphs to cercariae of a digenetic trematode

Cercariae of many digenean trematodes target particular developmental stages of their hosts. For some digeneans that are parasites of amphibians, infection appears timed to host metamorphosis. The success and timing of metamorphosis is itself affected by a number of factors, including host density. We investigated the degree to which rearing density of Rana pipiens larvae influenced time to metamorphosis and snout-to-vent length and mass at metamorphosis, as well as establishment of cercariae of the trematode Manodistomum syntomentera Stafford, 1905. As expected, individuals metamorphosed later, were smaller, and weighed less at metamorphosis if they were reared under intermediate to high densities compared with low densities, in experimental outdoor mesocosms. Cercariae establishment was higher in smaller metamorphs that took longer to metamorphose within the low-density treatment. Additionally, cercariae establishment was lower in larvae from the low-density tanks compared with larvae from the intermediate- to high-density tanks. However, more tadpoles had failed to metamorphose in the intermediate to high rearing densities by the time cercariae were no longer available from natural collections of first intermediate hosts, Physa spp. Larval amphibians under crowded conditions should experience increased susceptibility to trematode establishment in nature, but only if they metamorphose within the time period when cercariae are still available.     

石蒜总生物碱对家蝇的生物活性

在室内测定了石蒜总生物碱对家蝇的生物活性,表明石蒜总生物碱对家蝇具有一定的触杀作用和生长发育抑制作用.石蒜总生物碱不同浓度(15、12、9、6、3 mg/mL)、不同作用时间(24 h、36 h、48 h、60 h、72 h)以及它们的交互作用分别对家蝇幼虫和成虫的触杀作用有显著影响.当石蒜总生物碱的浓度为15 mg/mL时,家蝇幼虫(3龄早期)和成虫(羽化3d)平均校正死亡率最高,分别为40.96％和38.25％,随着浓度的降低,触杀作用逐渐降低,随着作用时间的延长,触杀作用逐渐增强,72 h的平均校正死亡率分别达39.35％和37.55％,但总生物碱对家蝇幼虫和成虫的触杀作用间无显著差异.处理24、36、48、60、72 h后,石蒜总生物碱对家蝇幼虫的LC50值分别为57.42、36.48、21.92、13.13和10.95 mg/mL,对成虫的LC50值分别为86.66、37.86、23.91、14.15和11.51 mg/mL.老熟幼虫的平均重量除了在3 mg/mL时与对照差异不显著,其他各浓度下都显著低于对照,而在各浓度下的化蛹率、蛹的平均重量和羽化率均显著低于对照.     

Cell differentiation during the ontogeny of larval salivary glands of the fly, Telmatoscopus albipunctatus

Using the larvae, pharate pupa, and pharate adults of the moth fly, Telmatoscopus albipunctatus, histological and ultrastructural features of the salivary glands were investigated. The gland lumen contains a milky secretion from the first instar. This secretion continues to ccur at all subsequent developmental stages; with the onset of the pharate pupal stage, however, the secretion becomes transparent and rather viscous. Histochemical tests revealed that it is mainly proteinaceous. Glands from the same developmental stage may respond differently to PAS-reaction.Various cell organelles were compared at consecutive stages of larval development and of secretory activity of the salivary glands. In first and second instar larvae autophagic vacuoles are virtually absent in the salivary gland cells. They were occasionally found in the third instar, when they appear to be engaged in the process of organelle turnover. Histolysis of the larval glands is initiated towards the close of the fourth instar when the number of autophagic vacuoles starts to increase. Simultaneously, the cytoplasm, previously full of ribosomes and endoplasmic reticulum, starts losing these structures. At the beginning of the pharate adult stage, the cytoplasm becomes practically devoid of all structures other than those engaged in autophagy.Polyteny of the chromosomes during ontogeny of the larval salivary glands is also discussed.     

Relationships among size, development, and Batrachochytrium dendrobatidis infection in African tadpoles

The fungal pathogen Batrachochytrium dendrobatidis contributes to the global decline of amphibians. Although mortality from B. dendrobatidis infections occurs primarily in postmetamorphic individuals, infected tadpoles may suffer reduced growth and developmental rates as a result of oral chytridiomycosis, possibly affecting adult fitness. We conducted a field study in which we examined South African tadpoles for oral chytridiomycosis and compared the body sizes of infected and uninfected individuals of 2 species, Heleophryne natalensis and Strongylopus hymenopus. Presence of B. dendrobatidis was determined by microscopic inspection of mouthparts. Infection prevalence was high in both species, 62.5 and 38.6%, respectively, and infected individuals were significantly larger in both species. The inclusion of developmental stage in the analysis of S. hymenopus body size eliminated the relationship between body size and infection status, suggesting that differences in body size were not due to differences in growth, but to differences in developmental stage of infected larvae. These results suggest that larvae at more advanced developmental stages are more likely to be infected with B. dendrobatidis and that infection in larval amphibians may be dependent on time or developmental status of larvae. Contrary to the results of past studies, there was no evidence that oral chytridiomycosis resulted in decreased growth of tadpoles, despite the occurrence of oral abnormalities in infected individuals of 1 species. Because tadpole performance can subsequently affect the health of anuran populations and because tadpoles can act as reservoirs of infection, the study of B. dendrobatidis in larval amphibians is important to understanding the effects of this emerging disease.     

Effects of insect hormones on hemagglutination activity in two members of the Culex pipiens complex

Effects of methoprene and 20-hydroxyecdysone on the development and hemagglutination activity (HA) were studied in both sexes of two members of the Culex pipiens complex-anautogenous C. p. quinquefasciatus and autogenous C. p. molestus. Juvenile hormone analogue (methoprene) and 20-hydroxyecdysone caused developmental changes in both mosquito strains. High larval mortality, prolongation of intermolt period in each larval instar and in the pupal stage, and morphological changes in the larval-pupal and pupal-adult transformations were also observed. Developmental changes were accompanied with some differences in the HA. HA was found in both sexes of both experimental mosquito strains. The juvenile hormone analogue used in the larval stage caused significant decrease of HA in the gut of adults of both sexes. On the other hand, 20-hydroxyecdysone decreased HA only in the female gut. Results obtained indicate that HA depends on the sex, the studied organ, and the level of hormones.     

Comparative delta-endotoxins of Bacillus thuringiensis against mosquito vectors (Aedes aegypti and Culex pipiens)

Pure crystals of seven Bacillus thuringiensis field isolates from the Lower Silesia region (Poland) were tested against larvae of Aedes aegypti L. and Culex pipiens L. (Culicidae, Diptera). The crystals of OpQ3 phylloplane isolate (belonging to the first biochemical type of B. thuringiensis subsp. japonensis, yoso, jinghongiensis) killed from 68 +/- 7% to 84 +/- 7% of the fourth instar larvae of A. aegypti. The crystals of two other strains (KpF3 and KpC1) of this group caused mortality between 3 +/- 2% and 70 +/- 7%. The LC50 ranged from 3.2 +/- 0.4 to 34.1 +/- 4.8 microg/ml. The effect of B. thulringiensis wratislaviensis H-47 crystals was the lowest with larval mortality from 0% to 17 +/- 3%. No significant (0%-37 +/- 6%) effect of B. thuringiensis crystals on the larvae of C. pipiens was observed. Our results show that the delta-endotoxins of B. thuringiensis act very specifically.